This reminds me of a segment in "The Moon Is A Harsh Mistress". Manny and the Professor visit earth, and on their tour tell every country they visit how this or that mountain or volcano or piece of high terrain is the perfect site for an earth-based escape-speed induction catapult, to reduce the cost of sending payload to the moon. Yep, Kilimanjaro was mentioned as a possible candidate.

Maybe we should think about that? (ducks... no, I am not taking this at all seriously...)

Yeah, I actually talked with the government in Ecuador about high-altitude launch sites back in the late '90s. Had we been able to put together about $250M in investment money, we mighthave made a go of it ...

I was actually about VTOL SSTO. Kind of F9R first stage. All you need is small takeoff-landing concrete field (about the size of floating spaceport-drone:) ).

PS I suppose there will be no benefit for Skylon. If it will be able to takeoff from such altitude at all.

Thinner atmosphere is a negative in landing, needs more dv to kill higher terminal speed. IMHO a spaceport-drone would make more sense than ruining some mountain slope. Airbreathing VTOL launch assist platform.

And you are right about Skylon, its T/O speed is supposed to be very high (~ Mach 0.5!) even at sea level. Maybe a free initial acceleration by sending it downhill? (JK)

SSTO rockets arent any riskier than any other space LV. But must require less infrastructure, something similar to small airport - few hangars, fuel deport, etc.

Vertical takeoff SSTO's have 2 risks. If the design goes slightly overweight or the engines slightly underperform it does not take off at all

The other fact is simply that SSTO's expect to lose 1/3 to 2/3 of the payload of a TSTO.

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They aren't much less riskier either.

You've been watching too much Skylon videos.

Actually Skylon is the odd one out in being much less riskier than VTOL SSTO's.

All aircraft and LV's have a "black zone" when engine failure will crash the vehicle, but an SSTO will have a longer period of that because it has no lift.

Skylon's winged lift uses 1/3 the thrust of its GTOW. If it's engines underperform or its structure is too heavy it still flies.

None of which is really relevant to where that runway is.

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- how does risk of "If the design goes slightly overweight or the engines slightly underperform it does not take off at all" applicable to VTOL SSTO more than to ANY other LV or even aircraft?And after all if VTOL device dont take off the ground there no risk at all or very low

- why "The other fact is simply that SSTO's expect to lose 1/3 to 2/3 of the payload of a TSTO" is a risk?Today we have a range of expendable LV with different performance, from very good payload fraction of 4-5%, to quite poor of around 1%. Somehow no one saying that those LV with low payload fraction a risky...

45% atmospheric pressure allow to use near vacuum optimized nozzle witch will produce high specific impulse right from take off, significantly reduced atmospheric drag and a little less gravitational drag.All this make mountain top makes VTOL SSTO more viable increasing its payload fraction.

Individuals have lived at 5950m (19500ft) for 2 years continuous http://www.ncbi.nlm.nih.gov/pubmed/12631426, and there is a Peruvian town of 7000 people at 5100m (16500ft), same as Everest base camp where normal westerners hang out for months at a time. You can be active at such altitudes without too many problems, though acclimatising takes 1-2 weeks. Having a bit more oxygen pumped into your buildings makes it a lot more comfortable.

Launching from altitude will typically cause a re-optimisation of initial acceleration to higher values that reduce gravity losses, as well as lowered aero losses for overall greater deltaV savings. It may also allow a more squat vehicle with reduced thermal protection area, lower re-entry peak temps/accelerations and reduced structural/hydrostatic pressure overheads and lighter aeroshells.

Chimborazo at 6250m and 1° from equator in Ecuador is probably best (If it was politically sound). And a funicular railway launch platform/tower could crawl up its side (or use a large cable car) from surrounding highlands at 3500-4000m to make life a bit easier.

Could be worth it for a return to launch site reusable TSTO like space X to squeeze the last few percent in cost or payload capacity out of the system in a highly competitive market, but as many have noted it makes most sense for SSTO where payload fractions are small and small gains in Isp, dry mass and deltaV reduction can have bigger impact.

A falling counterweight driven accelerating funicular/cablecar to raise lift off velocity to 50-100m/s would be a cheapish augmentation to save a bit more delta V.

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The glass is neither half full nor half empty, it's just twice as big as it needs to be.

Individuals have lived at 5950m (19500ft) for 2 years continuous http://www.ncbi.nlm.nih.gov/pubmed/12631426, and there is a Peruvian town of 7000 people at 5100m (16500ft), same as Everest base camp where normal westerners hang out for months at a time. You can be active at such altitudes without too many problems, though acclimatising takes 1-2 weeks. Having a bit more oxygen pumped into your buildings makes it a lot more comfortable.

I've been working for some periods at more than 5,000 m (with long periods of acclimatization at 3000) and I ensure you it is really demanding for an healthy westerner, specially if you have to spend the night there. Also, remember you wouldn't be selecting personnel among mountaineers or natives but among extremely good engineers and technician coming from any region of the US, etc.

So, "without too many problem" is really overstating, trust me... Not mentioning 7,000. At that altitude the risk of emphysema is large. O2 bottles and oxygen enriched environments still help but as soon as you work outdoor your brain becomes quite unreliable. I can't really see such a highly demanding business to be operated there.